Pyrometer for metallurgical furnaces



June 2, '1931. F. M. POOLE PYROMETER FOR METALLURGICAL FURNACES Filed Jan. 16, 1929 (Sf M Q A TTORNEY INVEN TOR. F05 7'51? M Raw 5 W. m I

Patented June 2, 1931 UNITED STATES PATENT OFFICE FOSTER M. POOLE, OF KANSAS CITY, MISSOURI, ASSIGNOR TO THE BROWN INSTRU- MENT COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA.

PYROMETER FOR METALLURGICAL FURNACES Application filed 'J'anuary 16, 1929. Serial li'l'o. 332,894.

My present invention relates to metallurgical furnaces normally utilized for roasting or otherwise treating finely divided ore, fullers earth or other material (hereinafter generically referred to as material) Such furnaces usually have superposed hearths and working chambers, the hearths having openings therein through which the material under treatment drops from each hearth to the hearth beneath, and suitable stirring and feeding devices in each working chamber v portions of some, and inner portions of other causing the material to pass over the hearth from thepoint of entryto the point .of discharge. a

The object of my invention is to provide a metallurgical furnace ofthe abovetype with simple and effective means for measuring and recording the temperature of the material in the working chambers.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and 4 forming a part of this specification. For a enclosing a series of superposed concentric '.Fig. 3isa better understanding of the invention, however, and the advantages possessed byit, reference should be had to-the accompanying I E drawings and descriptive matter in which I have illustrated and described preferred embodiments of the invention.

Of the drawings: V

Fig. 1 is an elevation with parts broken away and in section of a furnace incorporating my invention;

Fig. 2 is an enlarged elevation of a portion of the apparatus of Fig. 1;

plan view of the apparatus of Fig. 2;

Fig. 4 is an end view of one of the rabble arms;

Fig. 5 is a perspective of the blade bracket and pyrometer tube ready for assembly.

In the drawings I have illustrated a metallurgical furnace having a cylindrical hous-' ing A mounted on suitable supports A and means A In each hearth B are formed openings B for the downward passage of the material from said hearth onto the hearth below it, theseopenings being arranged at the outer hearths. The furnace has a revolvable structure comprising a central rotating shaft E which carries a plurality of radial arms F, each of which has a series of rabbles or blades G or equivalent stirring and feeding devices removably mounted thereon. The arms extend throughout the working chambers above the adjacent hearths. The shaft E is hollow and preferably provided with a refractory covering in order to protect it from the heat of the furnace. The shaft is connected for rotation at a point externally of and below the lowermost hearth with an electric motor The rabbles G in the up rmost working chamber 0 are so disposed as to feed the material outwardly from the inner portion of the hearth toward the outer delivery openings, while in the working chamber below, the rabbles are reversely arranged, so as to feed the material from the outer portion of the hearth toward the inner delivery openings therein, the rabbles in each of the other working chambers being so disposed as to similarly feed the material over the hearths from the point of supply to the point-of discharge. By these means the material is fed through the furnace in 'a zig-zag course.

The rabble carrying arms may be mounted on the shaft E in any desired manner, but in the form shown, extend through apertures in said shaft, and within said shaft are pref erably connectedwith air supply pipes (not shown) which convey cooling air throughout the longitudinal extent of the arm. A door A is arranged at one side of each working chamber and through which the rabble arms can be removed after being disconnected from the shaft E at the interior thereof. This may be performed without necessitating the cooling off of the furnace and suspension of operations.

In the construction shown the rabble arms F are formed with lower flanged portions F over which fingers H, of a'rabble holder H, are arranged to fit. The rabble is secured on the holder H at an angle'to the arm depending upon the desired direction of movement of the material upon which it operates.

I thermo-electric pyrometers are incorporated in such a manner as to render an accurate temperature record of the material in one or more working chambers. y,

The thermo-electric pyrometer, as shown, comprises a thermo-couple enclosed in a protecting tube K extending downwardly adjacent the rabble .and having a collar K secured thereon adjacent its outer end. The tube K is removably mounted in a slot M in a bracket M formed on one of the rabble holders Hand held therein by flanges M fitting over the collar K. The thermocouple tubecontaining the thermo-couple wires extends inwardly above the arm tofthe shaft E, through an opening E of which it passes to a terminal head 'K The opening E is closed with fireclay and by a fitting tube holding E on the inner side of the shaft. The thermo-couplewires are detachably connected at the terminal head to suitable leads enclosed in a second tube N connecting the head to an indicating and recording instrument P. The latter is advantageouslymounted on a portion of the revolvable structure protected from the furnace and accessible to the operator, preferably on the outer side of the'shaft E below the lowermost hearth. I p

The described arrangement provides an intimate contact between the lower portion of the thermo-couple protecting tube and the material being treated due to the extension of the tube below the surface of the material, and the temperature of the material is accurately transmitted to the instrument I. The thermo-couple apparatus mounted on the arm may be removed separately from, or with, the corresponding rabble arm through .the adjacent housing door. The arrangement of the parts in the present construction eliminates the necessity for sliding or brush contacts in the thermo-coup1e circuit. This is especially-desirable in view of the low electric potential present in the thermo-couple circuit in which a small resistance would produce considerable errors in the recording instrument. Where the recording instrument comprises a hand wound clock, no external connections are necessary. When, however, the recording instrument is electrically driven, the instrumentmotor is connected to a suitable source of electric energy through contacts in sliding engagement with stationary slip rings Q, surrounding the lower end of the shaft E. 1

While in accordance with the rovisions of the statutes, I have illustrate and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secureby Letters Patent, is:

1. The combination, with a furnace having at least one hearth and at least one rabble carryin arm sweeping over the hearth, and a rotatably driven shaft carrying said arm, of a thermo-responsive element supported by said arm in a position to contact with the surface layer of material on the hearth and'to be protected by' a rabble from direct erosive action by the material, a temperature exhibiting instrument mounted on said shaft, and means directly connecting the element'and instrument for transmitting the temperature responsive effect therebetween.

2. The combination, with a furnace having at least one hearth and at least one rabble carrying arm sweeping over the hearth, and a rotatably driven shaft carrying said arm, of a thermo-electric element supported by said arm in a position to contact with the surface layer of material on the hearth and to be protected by a rabble from direct erosive action by the material, a temperature exhibiting instrument mounted on said shaft, and electrical connections uninterruptedly joining the element and the instrument.

3. The combination, with a furnace having at least one hearth and at least one rabble carrying arm sweeping over the hearth, and a rotatably driven shaft carrying said arm, of a thermo-electric element supported by said arm in a position to contact, with the surface layer of material on the hearth and to be protected by a rabble from direct erosive action by the material, a temperature exhibiting instrumentv mounted on said shaft, said instrument having auxiliary electrical power means,'slip rings on the shaft for connection with an exterior source of electrical energy, electrical connections joining the slip rings and the auxiliary electrical power means, and electrical connections uninterruptedly joining the thermo-electric element and the instrument.

Signed at Kansas City, in the county of Jackson and State of Missouri, this 11 day of January A. D. 1929.

- FOSTER M. POOLE. 

